Do I need to use Multiple Modx in the same server, if I do this?

Hi, there, I know this is a stupid question, but I like to make sure what I think is correct.

I intend to create a site with multiple sub-domains, e.g. 123.abc.com ... 234.abc.com 456. abc.com, I assume, I need to upload a copy each to each subdomain and use different or same database for all of them, correct? or is there another way? thanks.

You could do each site in it’s own container and use this: http://www.modxcms.com/Subsites-Subdomains-825.html

Or if you want more clear separation between the sites, you could use this (requires hacking modx files, so causes extra work when upgrading modx):
http://modxcms.com/Subsites-the-MAD-HACK-2.0-1435.html

Wow, I am impress with Modx, this is one powerful application! Question, if somewhere down the line that I might consider to move one or more sub-domain to its own site which hack I should use, or I should do as I was thinking? thanks.